Problem: Simplify the following expression: $t = \dfrac{p}{9} + \dfrac{9p}{8}$
In order to add expressions, they must have a common denominator. The smallest common denominator is the least common multiple of $9$ and $8$ $\lcm(9, 8) = 72$ $ t = \dfrac{8}{8} \cdot \dfrac{p}{9} + \dfrac{9}{9} \cdot \dfrac{9p}{8} $ $t = \dfrac{8p}{72} + \dfrac{81p}{72}$ $t = \dfrac{8p +81p}{72}$ $t = \dfrac{89p}{72}$